using System;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Math;

namespace Org.BouncyCastle.Asn1.Pkcs
{
	public class MacData
		: Asn1Encodable
	{
		internal DigestInfo	digInfo;
		internal byte[]		salt;
		internal BigInteger	iterationCount;

		public static MacData GetInstance(
			object obj)
		{
			if (obj is MacData)
			{
				return (MacData) obj;
			}

			if (obj is Asn1Sequence)
			{
				return new MacData((Asn1Sequence) obj);
			}

			throw new ArgumentException("Unknown object in factory: " + obj.GetType().FullName, "obj");
		}

		private MacData(
			Asn1Sequence seq)
		{
			this.digInfo = DigestInfo.GetInstance(seq[0]);
			this.salt = ((Asn1OctetString) seq[1]).GetOctets();

			if (seq.Count == 3)
			{
				this.iterationCount = ((DerInteger) seq[2]).Value;
			}
			else
			{
				this.iterationCount = BigInteger.One;
			}
		}

		public MacData(
			DigestInfo	digInfo,
			byte[]		salt,
			int			iterationCount)
		{
			this.digInfo = digInfo;
			this.salt = (byte[]) salt.Clone();
			this.iterationCount = BigInteger.ValueOf(iterationCount);
		}

		public DigestInfo Mac
		{
			get { return digInfo; }
		}

		public byte[] GetSalt()
		{
			return (byte[]) salt.Clone();
		}

		public BigInteger IterationCount
		{
			get { return iterationCount; }
		}

		/**
		 * <pre>
		 * MacData ::= SEQUENCE {
		 *     mac      DigestInfo,
		 *     macSalt  OCTET STRING,
		 *     iterations INTEGER DEFAULT 1
		 *     -- Note: The default is for historic reasons and its use is deprecated. A
		 *     -- higher value, like 1024 is recommended.
		 * </pre>
		 * @return the basic DERObject construction.
		 */
		public override Asn1Object ToAsn1Object()
		{
			Asn1EncodableVector v = new Asn1EncodableVector(digInfo, new DerOctetString(salt));

			if (!iterationCount.Equals(BigInteger.One))
			{
				v.Add(new DerInteger(iterationCount));
			}

			return new DerSequence(v);
		}
	}
}
